[LEDE-DEV] [PATCH RFC v3 3/3] ath9k: parse the device configuration from an OF node

[Christian Lamparter]

On Saturday, June 25, 2016 05:08:29 PM Martin Blumenstingl wrote:
> On Sat, Jun 25, 2016 at 2:01 PM, Christian Lamparter
> <chunkeey at googlemail.com> wrote:
> > On Friday, June 24, 2016 02:34:30 PM Martin Blumenstingl wrote:
> >> This makes it possible to configure ath9k based devices using
> >> devicetree. That makes some out-of-tree "convert devicetree to
> >> ath9k_platform_data glue"-code obsolete.
> >
> > Hm, what about the embedded ath9k pcie chips that need the early
> > pci-fixup routine for the device to work properly [0], [1]? How
> > will this be handled/integrated? I know that the ar71xx and the
> > lantiq platforms use similar pci-fixup routines that need a few
> > bytes from the eeprom/cal data. So lantiq has a few extra properties:
> > "ath,pci-slot", "ath,device-id" and "ath,eep-flash".
> that is exactly the use-case I want to use your owl-loader for (see
> [0], it's a small kernel module which adds the PCI configuration for
> ath9k devices).
Well, we also cooked up a userspace hack for OpenWRT/LEDE which would
work with the existing code (for the case you mentioned below) [2]. 
Furthermore it also works for other devices, as long as the fw is in
/lib/firmware and not in a subdirectory (But this can be fixed in 5
minutes with better bash foo). One thing that needs to be considered
though: That script interferes with procd firmware loading if the
"timing" is right. However usually procd has already finished all
firmware requests by then.

> This makes ath,pci-slot and ath,eep-flash obsolete.
> As far as I'm aware ath,device-id is a bit of a special case (mtd_read
> issues when the caldata is stored at an unaligned position on NOR
> flash). So this might be obsolete as well when using owl-loader.

The problem with the owl-loader is/was that it sticks around
when it has initialized all the cards. Unloading a module by
itself is tough. One way out would be to add it to ath9k's pci.c.
The question is: will such a feature have support from the ath9k
folks?

> > As an example: the AR9280 in the Cisco Z1 AP is initially
> > 0x168c:0xff1f (<-- ath9k doesn't know about that id). The
> > pci-fixup routine will change it to  0x168c:0x002A. Only
> > then ath9k can take it over and will initialize it.
> > Thing is: this is all currently done by platform code for
> > those architectures... And currently, the request_firmware
> > doesn't work for caldata on UBI partitions.
> request_firmware is working on UBI partitions in many cases.
> It's just not working when request_firmware is called too early (and
> this is not UBI specific, other filesystems might be affected as
> well): if it is called before rootfs is mounted (which is the case
> when you call it from a PCI fixup function) then it's not working
> (like you said).
> The "solution" to this is to compile the driver as kernel module (once
> this is loadable everything else should be readable as well).
> Not only ath9k is affected by this "issue", this is simply a
> limitation of request_firmware and/or the linux boot chain.
> 
> A few words regarding your owl-loader:
> First of all I would like to say "thank you"!
> Mathias and I are working on changing the lantiq target in LEDE to use
> owl-loader for all (ath9k) devices.
> All I had to do was to add another OWL PCI ID, implement a fallback
> for the firmware filename when there is no ath9k_platform_data (I'm
> using the same pattern as in PATCH 3/3 in this series). You can find
> the WIP code here: [1]

I've added lede-dev and Luis since this is relevant for them.
Maybe between the sysloadfw.sh and owl-loader, there's another
solution we overlooked so far? I know Luis has been digging
around in the firmware_class and added the sysdata API. But
from what I can tell, this would ?break? LEDE/OpenWRT's
userspace helper, since the sysfs interface in 
/sys/class/firmware which is used by procd to upload the data
is gone with sysdata or am I wrong?
 
Regards,
Christian

> [0] https://patchwork.ozlabs.org/patch/607682/
> [1] https://github.com/xdarklight/source/commits/ath9k-owl-loader-20160624
[2] <https://github.com/riptidewave93/Openwrt-Z1/commit/9a38c60a1206b4010fbfb626fc7b2ec69bbe232a>